Abandoning your dedicated MPLS network for fast Internet connections and IP VPNs can help you slash WAN costs. However, it isn’t for everyone.
For more than a decade, MPLS-based VPNs have been the technology of choice for private WAN connectivity services, thanks to the security and reliability features. Enterprises flocked to MPLS as it offered an innovative way to connect network services, compared to alternatives such as Frame Relay. Though MPLS deployments have been mainstream for a while now, the technology still remains expensive.
However, now is an excellent time to be re-evaluating your WAN strategy with the availability of new technologies such as Ethernet services or even plain old Internet. Replacing your expensive MPLS pipes with carrier Ethernet or commodity Internet can bring huge savings, if you can deal with the downsides.
“Yes, there is a face value cost saving in migrating from a dedicated private MPLS solution to a commodity Internet service. MPLS services are typically charged on some form of managed fixed access radio network “last mile” connection plus the general support and service costs around the MPLS network service itself. Commodity Internet provides you with the ability to choose from a wider array of ISP connections which allow you to create a WAN network, typically using IPSec,” says Ken Philcox, Senior Consultant, Intergence Systems.
Paulo Pereira, Systems Engineering Manager, Cisco, says there are technologies that allow companies to run a VPN over the Internet that offer acceptable levels of security and connectivity, but most likely the missing component will be the lack of Service Level Agreement from the Service Provider. For an enterprise whose business depends on the connectivity between its sites a careful assessment should be made between the potential savings versus the potential losses from the lack of a proper enterprise grade SLA.
“The fundamental difference between an MPLS VPN service and an Ethernet based service is that of layer 3 versus layer 2. A layer 2 based service such as Multipoint Ethernet presents the SP network to the client as a big Ethernet switch where every port can communicate with every other port as if they were sharing the same switch. Whereas for small networks this presents itself as an interesting proposition, as the number of endpoints increase, the proposition becomes less and less interesting,” he adds.
Hatem Bamatraf, Executive VP of Network Development and Operations, du, says MPLS is still the dominant WAN technology and constitutes a major demand from its domestic and multi-national customers. “MPLS is optimised to support real time traffic and we don’t see any major benefit from migrating away from MPLS. Deploying Ethernet services will still mean that the traffic has to be optimised through the core. Though this adds to some additional complexity, but it is still simpler than MPLS deployments. So really, it’s a matter of choice.”
Though there are trade-offs in terms of performance and bandwidth, the shift from legacy technologies to Ethernet and IP VPNs is primarily driven by costs in a world where budgets are continually restrained. Many organisations seek to reduce the costs of their WAN solution, and so they turn to Ethernet services which can be as much as 25% cheaper than a frame relay option. When compared with private line services, the cost benefit Ethernet offers is even greater,” says Simon Parry, Carrier Ethernet consultant at Ciena.
The limited supply of credible carriers coupled with the risk-averse behaviour of enterprise WAN managers to the lack of QoS and imperfect realiability and predictability over the Internet has led to private WAN services still being the preferred choice for connecting branch and distributed locations.
Pereira from Cisco explains why: “The same way network architects segment layer 2 networks with routers to increase the scalability of a network, a large collection of spoke sites is better off connected using a layer 3 technology rather than a layer 2 technology. The considerations should be around the number of sites being interconnected as well as the requirements in terms of traffic path manipulation. Adding too many endpoints into a layer 2 connection starts to present scalability issues. A layer 3 technology such as MPLS VPNs also presents better options to achieve the desired traffic flows.”
Bamatraf from du agrees: “ It is not recommended to use Ethernet for large numbers of branches and requires routers at the carrier edge to prevent broadcast storms. Instead, most Ethernet deployments for branch sites are simply used as an access protocol to an MPLS service.”
WAN virtualisation to the rescue
The emergence of WAN virtualisation is giving rise to the next-gen enterprise WAN architecture by solving the reliability and performance predictability issues associated with use public Internet transport. It is now enabling enterprises to take advantage of the carriers’ huge and ongoing investments in wired and wireless public Internet connectivity for their corporate Intranets.
“WAN virtualisation delivers significant cost benefits in that it greatly reduces the price per bit of bandwidth for enterprise Intranet. By addressing the reliability and performance issues associated with public internet, WAN virtualisation helps enterprises reduce their infrastructure investments especially in situations such as connectivity to remote locations,” says Samer Ismair, Systems Engineer at Brocade.
He adds that the advantage of WAN virtualisation is that it combines multiple WAN connections including private WAN as well as Internet WAN links like DSL, cable, fibre, etc. This aggregation enables much more bandwidth per enterprise location, because of its ability to aggregate multiple, disparate links and use the combination as if it were a single connection.
Though WAN virtualisation holds lot of promise, replacing your expensive WAN connections with alternatives isn’t as simple as picking a new vendor and having new circuits installed. Unfortunately, there is a lot more to it. You need to wade through an ocean of contracts and terms, find which vendors serve all your locations, and be ready to navigate through service providers promising you everything, only to discover they deliver a fraction of what they promised.
The old way is proven and realiable. But in this economy in which everyone has to cut corners, your WAN is no exception and options are now available to build something similar on the cheap. Just be sure to insist on some kind of redundancy, even if it is only a DSL or cable modem.
